1. Field of the Invention
The invention relates to an apparatus for the production of ring-shaped bodies from concrete, such as pit linings, pipes or the like.
2. Background Discussion
Due to the releasable connection between the pressing head and the upper mold faucet devices for the production of circular ring-shaped or oval concrete pipes, pit linings or other molded bodies have the practically important advantage that the upper mold faucet may remain on the yet plastic ring-shaped body as a kind of protective cap after the molding operation and will thus protect the delicate upper centering end from damage during transport or in the drying area. To this end it is known, for example, from German patent 33 23 340, to leave the upper faucet forming a mold cover on the molded concrete body until it has sufficiently hardened, and to releasably fix it to the piston head by means of a positive catch coupling during the molding operation. The coupling device requires an exact positioning of the upper mold faucet with respect to the pressure head so that the coupling elements to be positively connected can actually be effectively connected.
Further, a production facility for reinforced concrete pipes preferably having an oval cross section is known from U.S. Pat. No. 3,696,182 in which a special coupling device is provided for attaching and releasing the upper mold faucet to and from a faucet mount. The coupling device consists of motor-driven, liftable and lowerable rods guided along the sleeve of a hollow cylindrical support head, a radial collar being formed on the bottom end of each of the rods. The collars engage special pockets formed in a circumferential wall of the mold faucet during a coupling operation. The axially acting support forces for the mold faucet are the result of the positive connection between the collars of the rod ends and the integrated pockets also in this case so that, in this case too, no coupling effect based only on clamping forces is present.
In another production device for hollow concrete bodies known from European patent publication 0 675 787, a coupling device is used to establish a non-positive engagement of a mold faucet on an upper ring collar, the coupling device consisting of a dimensionally stable ring-shaped body, a flexible pressure tube disposed thereon, and a divided clamping ring. For establishing an engagement with a previously positioned mold faucet the ring-shaped body rigidly attached to the pressure head is clapped over the ring-shaped collar of the respective mold faucet, and the clamping ring is continuously and firmly pressed to the outer wall of the ring-shaped collar by blowing up the flexible ring-shaped tube. Thereafter the mold faucet may be placed on the upper end of the mold or the molded material by a corresponding movement of the pressure head and turned back and forward while applying an axial pressure around the mold axis. To release the clamping connection the ring-shaped tube is emptied, and the clamping ring is spread open by internal springs. For enabling a vertical removal of the exterior mold even with the coupling device activated the outer diameter of the coupling device is smaller than the inner diameter of the exterior mold so that the latter can be pulled up without colliding with the coupling device. A disadvantage of the known device is, among others, the insufficient adjustment of the coupling device to different mold faucet sizes due to the small free space between the ring-shaped collar and the clamping ring when the tube is deflated. Further, the device is technically complex since it requires a pressure air supply including a corresponding control means. Finally, disturbances of the production processes often occur which are caused by the entry and deposition particularly of granular concrete components into the ring-shaped gap of the coupling device and damage to the flexible ring-shaped tube possibly caused thereby.
Finally, a related device for the production of molded concrete bodies provided with clamping tongs distributed on the circumference of the pressure head as a coupling device is known from European patent 0 351 325. To assure an engagement and release of the upper mold faucet without disturbances a ring collar directed upward is formed on the mold faucet, the two clamping jaws of the tongs establishing an engagement with the ring collar during a closing operation. The clamping tongs are provided with tong arms pivotable about central tappet bearings, the clamping jaws as well as a spreading spring being disposed on the lower arm portions and a hydraulic cylinder being disposed between the upper arm portions. Further, centering struts vertically fixed to the pressure head turnable back and forward by means of a motor are allocated to the coupling device, the struts enabling a previous centering of the coupling faucet in its engagement position. Such devices have been well tried in practice in connection with rigid mold faucets integrally formed of corrosion resistant steel since they are robustly built and can be operated with technically simple means. However, the outer diameter of the coupling device is larger than the inner diameter of the exterior mold in this case so that the exterior mold can not be drawn over the coupling device. Instead, it is necessary to release the clamping tongs and to remove the coupling device before the exterior mold is pulled off. To prevent an accompanying detachment of the upper mold faucet due to clinging effects, special holding-down devices for the mold faucet are required.
It is a primary purpose of the invention to provide a device for the production of ring-shaped bodies of concrete enabling a minimization of operational disturbances and production-technically optimized operational processes, for example, the removal of the exterior mold with the coupling device activated.
According to the invention, the purpose is satisfied by providing each of the clamping units referred to as clamping tongs with a pressure cylinder, the cylinder housing of which, being disposed on the radially inner side, is fixedly connected by means of at least one tension strut with the radially outer clamping jaw or its clamping jaw sustainer and the piston of which, being effective radially outward, engages the radially inner clamping jaw.
The arrangement and formation of the different components according to the invention results in a safely operating and compact coupling device the operation of which cannot be affected by the entry of concrete parts. The arrangement of the cylinder housing at the radially inner side of the inner clamping jaw sustainer and the mechanical coupling of the cylinder housing movable in the effective direction with the radially outer clamping jaw sustainer has the effect that only a relatively narrow part of the whole coupling device is disposed on the outer side of the ring-shaped collar and that the outer diameter of the whole coupling device is smaller than the inner diameter of the exterior mold. Thus the exterior mold can be drawn off upwardly over the coupling device with the coupling device activated and therefore the mold faucet being held down. During a clamping operation, the piston of the cylinder unit acts on the inner clamping jaw sustainer in the radial direction while simultaneously the cylinder housing is moved radially inwardly by the hydraulic inner pressure. Due to the mechanical coupling to the radially outer clamping jaw sustainer it is taken along by the cylinder housing, that is, moved radially inwardly by the same amounts. The equally set opposed movements of the two clamping jaw sustainers will finally result in a tight attachment of their clamping jaws to the two sides of the ring-shaped collar. Since a plurality of clamping units is provided so as to be angularly displaced, a fixed engagement of the pairs of clamping jaws is effected after an initial fine centering of the previously positioned mold faucet, and thereby a positive fixation of the mold faucet on the pressure head in an exactly centered position is obtained.
For the maintenance of the shiftability of at least one clamping jaw and the cylinder housing, each clamping unit or clamping tong is preferably provided with a bridge fixed to a base plate of the pressure head, a radially oriented guiding rod on which the cylinder housing including the mechanically coupled outer clamping jaw sustainer as well as the inner clamping jaw sustainer are each slidably borne being fixed between the radially inner and outer limb of the bridge.
For an optimized operational safety an intercepting device for preventing an unintended detachment of the mold faucet from the clamping units is allocated to the coupling device formed according to the invention. To this end interception hooks protruding downwardly are provided on the clamping units, the interception hooks engaging correspondingly formed catch elements thus safely preventing a drop of the mold faucet.
A further object of the invention is a newly designed mold faucet for shaping the upper centering end of a molded concrete body to be used in one of the production devices described above. The mold faucet consisting of a shaping faucet part and an upper ring-shaped collar is provided with at least one engagement surface for at least one clamping element or clamping jaw of the coupling device on the upper end portion of the ring-shaped collar as well as a catch element for an interception hook below the engagement surface. The ring-shaped collar is disposed in the central portion of the faucet part and is either integrally formed with or fixedly welded to the latter.
As compared to known mold faucets the ring-shaped collar has a much larger height which approximately equals the height of the shaping faucet part.
The centering of a single upper faucet in the central axis of the device is efficaciously effected previous to or during the engagement of the clamping tongs with the aid of centering rods provided on the pressure head and protruding downward, the inclined surfaces of which slidably engage the upper and correspondingly formed end of the ring-shaped collar of the upper faucet during the lowering movement of the pressure head and will push the upper faucet into the central position.